1. Field of the Disclosure
The present disclosure relates generally to components useful in rotating systems such as automobile transmissions, torque converters and automatic clutches. The present disclosure relates more particularly to seal rings useful in rotating systems such as oil-lubricated systems and pneumatic systems, and methods for making such seal rings.
2. Technical Background
Seal rings are commonly used in assemblies like transmissions and clutches to limit fluid leakage and pressure loss, especially in parts of the assemblies under high pressure. These are typically used in rotating connections in conjunction with a liquid such as an oil or other lubricant.
An example of a conventional rotating connection is shown in perspective schematic view in FIG. 1. Here, a seal ring is disposed about a rotating shaft at a joint thereof, in a groove such that it seals against the surrounding housing. The seal ring is fixed neither to the shaft nor the housing, so that it can rotate with respect to either or both. The seal ring itself has three sealing faces, as shown in the cross-sectional schematic view of FIG. 2. The outer circumferential face of the seal ring seals against the housing in which the shaft and seal ring are disposed. One of the lateral faces seals against the sidewall of a groove formed in the shaft. In many cases, only one of the lateral faces is actually sealed against a surface when installed. Nonetheless, seal rings are typically made to be symmetric, so that they can be installed without regard to which direction they face. Accordingly, a seal ring needs to have three faces that are sufficiently flat and circular to seal against a cooperating surface (i.e., of a groove or of a housing).
Seal rings typically have two ends that can engage with one another to provide an overall circular seal in operation, but can be disengaged to allow a seal ring to be slipped over an already-installed shaft, e.g., of a transmission. As the person of ordinary skill in the art will appreciate, the first end and the second end of a ring seal can engage one another in various manners. It is desirable that the ends can move relative to one another, e.g., to slightly expand or contract the circumference of the circular seal, in order to accommodate different tolerances and expansions. For example, FIG. 3 provides partial perspective schematic views of a number of conventional examples of engageable first and second ends for seal rings including a butt joint, a hook joint, a bias joint, a 2-L joint, and a 2-T joint.
It is important for a seal ring to remain in a substantially circular configuration, both with respect to radial deformations and with respect to planar deformations. Any significant out-of-roundness can cause a seal ring to fail to provide a sufficient seal, and thus cause an assembly including such an out-of-round seal ring to fail. And deformations in a seal can cause the seal to be damaged when being installed, especially at its ends, which can cause critical failures with respect to fluid leakage.